This isn't directly about Widgets, but a somewhat related question: I would like to host a customized Web Application made via the javascript web app builder on my own web server, yet allow users of my organization to seamlessly authenticate through the ArcGIS Online Platform.
The ideal workflow would be: User logs into my ArcGIS Online organizational account --> finds the app item (basically a reference to the web apps URL) in a group he has access to --> gets redirected to that URL --> does NOT need to sign in again to ArcGIS Online via this dialog that opens.